Momo I Marmoset
Learns from and imitates others.
University of Vienna, Austria
DON'T LET THE WALNUT-SIZE BRAIN fool you. Western scrub jays
(right) do some real reasoning, says University of Cambridge profes
sor Nicky Clayton. They will move a food cache if another jay sees
them hide it, recalling when they themselves were thieves. Clayton
says jays also spontaneously plan for tomorrow's breakfast, basing
food stores on future hunger regardless of current needs. Common
marmosets, as infants, learn what to eat by watching elders and, like
apes, can imitate others' actions-one of the most complex forms of
learning. (They even have a sense of "object permanence"-knowing
that something out of sight still exists.) But, says Friederike Range
of the University of Vienna, the primates' short attention spans may
keep them from developing more complex behaviors.
58 NATIONAL GEOGRAPHIC * MARCH 2008